Standard time and frequency station

While listening to AM on a transistor radio, in many places on the AM band I can hear a faint standard time station sending one second ticks and the only identifier is , "rr", sent on cw. This is certainly due to some kind of mixing product that winds up on the I.F. but I wonder what time station this is. Does anyone know?

Unfortunately, in addition to the sonorous voices of the Radio Reloj locutores (announcers) and the metronome’s pleasant tocking, the beginning of each subsequent news story is preceeded by a telegraphed—literally—signal in Morse Code (“R.R.” for Radio Reloj), similar to the ones which introduced Walter Winchell’s commentaries on U.S. radio and television during the 1940’s and 1950’s. Hence, I’d be drifting off to sleep when—!DIT-DOT-DIT, DIT-DOT-DIT!—I’d be jarred awake! - See more at: